Echogenic surface for enhanced ultasonic visibility

ABSTRACT

An improved medical device, such as a needle, has a surface which enhances the “echogenicity” or ultrasound visibility of the medical device so that the medical device can be guided inside a human body using ultrasound imaging. In one embodiment, concave slots are formed on the surface of the improved medical device to enhance the ultrasound visibility of the improved medical device. The surface of each concave slot is substantially flat in a radial cross section of the needle and curved in an axial cross section of the improved medical device.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The field of the invention relates generally to echogenicsurfaces, and more particularly, to echogenic surfaces for medicalinstruments, e.g., needles used in medical procedures, to enhance theultrasonic visibility of the medical instruments.

[0003] 2. Background

[0004] Needles are commonly used in various medical procedures, such asbiopsy and amniocentesis procedures, to gain percutaneous access intothe body. In a biopsy, for example, a biopsy needle is inserted into thebody to collect a tissue sample from a tumor. In amniocentesis, anaspiration needle is inserted into the amniotic sac to collect amnioticfluid.

[0005] These medical procedures are frequently monitored using animaging technique. One widely used imaging technique is ultrasonography,which is commonly used to image the development of a fetus.Ultrasonography relies on the “echogenicity” or ultrasonic visibility oforgans and bones, and medical instruments placed inside the body. In abiopsy, ultrasonography is used to guide the biopsy needle to the tumorsite. In amniocentesis, ultrasonography is used to guide the aspirationneedle inside the amniotic sac to avoid injury to the fetus.

[0006] In order to guide a needle inside the body using ultrasonography,the needle must be visible in an ultrasound image. Unfortunately, thesmooth cylindrical surface of a needle is very difficult to image usingultrasonography. FIG. 1 illustrates a medical device 20 (e.g., a needle)of the prior art shows ultrasound waves 10 emitted from a transducer 15striking the surface of the device 20. The device 20 reflects theultrasound waves 10 in a direction 25 away from the transducer 15. As aresult, the emitted ultrasound waves 10 are not returned to thetransducer 15 and the device 20 is not imaged.

[0007] To address this problem, various methods have been developed toenhance the “echogenicity” or ultrasonic visibility of a medical device,which problem can be worse for a thin device such as a needle. Thesemethods typically involve providing a disrupted surface at the distalend or tip of the medical device or needle to enhance its ultrasonicvisibility. Current methods for providing disrupted surfaces on a needleinclude forming rings around the outer and/or inner cannula of theneedle, sandblasting the needle surface, chemically etching the needlesurface, drilling holes through the cannula of the needle, and coatingthe needle surface with a polymeric coating. The resulting disruptedsurfaces enhance the ultrasonic visibility of the needle byisotropically scattering incident ultrasonic waves. FIG. 2 illustratesan example of a prior art needle 30 with a disrupted surface 35 at itsdistal end. FIG. 2 shows ultrasound waves 10 emitted from a transducer15 striking the disrupted surface 35 of the needle 30. The disruptedsurface 35 reflects the ultrasound waves 10 in random directions 40 withsome of the waves being reflected back to the transducer 15 and some ofthe waves being reflected away from the transducer 15. The reflectedwaves received by the transducer 15 are used to create an ultrasoundimage of the needle.

[0008] Another method to enhance the ultrasonic visibility of a needleis to form dimples on the needle surface. FIG. 3A illustrates a sideview of a prior art needle 50 with dimples 55 formed along its surface.FIG. 3B shows a radial cross sectional view of the prior art needle 50of FIG. 3A. FIG. 3B shows ultrasound waves 65 striking one of thedimples 55 from a transducer 60. The dimples 55 reflect the ultrasoundwaves in different directions 70 with some of the waves being reflectedback to the transducer 60 to form an ultrasound image and some of thewaves being reflected away from the transducer 60.

[0009] Although the usefulness of etched, coated and sandblastedsurfaces has been demonstrated, these disrupted surfaces typically haverandom disruptions that scatter incident ultrasound waves with no realdirection. In addition, the dimples 55 only direct ultrasound waves thatare reflected off of a single point on its surface back to thetransducer. The rest of the ultrasound waves are directed away from thetransducer.

[0010] Therefore, there is a need for an echogenic surface that reflectsmore of the ultrasound waves back to the transducer. Such an echogenicsurface would provide improved ultrasonic visibility of medicalinstruments, such as needles. This would make it easier for physiciansto guide the medical instruments inside the body using ultrasonography.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The components in the figures are not necessarily to scale,emphasis instead being placed upon illustrating the principles of theinvention. Moreover, in the figures, like reference numerals designatecorresponding parts throughout the different views. However, like partsdo not always have like reference numerals. Moreover, all illustrationsare intended to convey concepts, where relative sizes, shapes and otherdetailed attributes may be illustrated schematically rather thanliterally or precisely.

[0012]FIG. 1 is an illustration of a prior art needle having a smoothsurface and shows ultrasound waves from a transducer striking theneedle.

[0013]FIG. 2 is an illustration of a prior art needle having a disruptedsurface at its distal end and shows ultrasound waves from a transducerstriking the needle

[0014]FIG. 3A is a side view of a prior art needle with dimples formedalong its surface.

[0015]FIG. 3B is a radial cross section of the prior art needle in FIG.3A.

[0016]FIG. 4A is a schematic illustration of a side view of an improvedmedical device with concave slots formed on the surface of the needle.

[0017]FIG. 4B is a schematic illustration of a radial cross sectionalview of the medical device in FIG. 4A.

[0018]FIG. 4C is a schematic illustration of an exploded side view ofthe medical device in FIG. 4A.

[0019]FIG. 5 is a schematic illustration of an example arrangement ofconcave slots formed on the surface of the improved medical device.

[0020]FIG. 6 is a schematic illustration of another example arrangementof concave slots formed on the surface of the improved medical device.

[0021]FIG. 7 is a schematic illustration of a radial cross sectionalview of another example embodiment of an improved medical device havingconcave slots formed on the surface of the medical device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022]FIG. 4A is a schematic illustration of a side view of an improvedmedical device 110 with concave slots 115 formed on the surface 120 ofthe medical device 110. The improved medical device 110 may be anydevice intended for use within a human body such as a needle orcatheter. In order to demonstrate an example, the improved medicaldevice 110 may be referred to as a needle. However, references to any ofthe improved medical devices as a “needle” should not be construed tolimit the medical device to needles.

[0023] The surface 120 may be made of the same or different material asthe rest of the improved medical device 110. The surface 120 may be, forexample, stainless steel or plastic. The concave slots 115 preferablyare located near or at the location of the improved medical device 110which the physician desires to image. Thus, for a needle, the concaveslots 115 may be located near the distal end or tip of the needle. Theconcave slots 115 may be formed on the surface 120 of the needle 110using a variety of techniques, including drilling, milling, etching, orpressing.

[0024]FIG. 4B is a schematic illustration of a radial cross sectionalview of the improved medical device 110 of FIG. 4A. The surface of eachconcave slot 115 is substantially flat or straight 125 in the radialcross section. As shown in FIG. 4B, ultrasound waves 130 strike the flatsurface 125 of one of the concave slots 115 from a transducer 135 thatis aligned with the flat surface 125. The ultrasound waves 130 arereflected off of the entire flat surface 125 of the concave slot 115 ina direction 140 back to the transducer 135. In contrast, the dimple 55of the prior art only reflects ultrasound waves off of a single point onits surface back to the transducer, with the rest of the ultrasoundwaves being reflected away form the transducer. Thus, the concave slots115 of the improved medical device are able to reflect more of theultrasound waves of the transducer 135 back to the transducer 135 thandimples 50, thereby providing a brighter and less interrupted ultrasoundimage.

[0025]FIG. 4C is a schematic illustration of an exploded side view ofthe improved medical device 110 of FIGS. 4A and 4B. Each concave slot115 has a curved surface 145 in the axial cross section. The curvedsurface 145 may be hemispherical, oval, or the like. The curved surface145 of each concave slot 115 in the axial cross section enables theconcave slot 115 to reflect “off axis” ultrasound waves 150 back to thetransducer. The “off angle” ultrasound waves 150 are ultrasound wavesthat approach the concave slot 115 at an angle with respect to the axis155 of the improved medical device 110. By increasing the curvature ofthe curved surface 145, each concave slot 115 is able to reflect “offaxis” ultrasound waves 150 at more acute (i.e., steeper) angles withrespect to the axis 155 of the improved medical device 110. This featureis desirable when the transducer becomes orientated at an acute anglewith respect to the axis 155 of the improved medical device 110, whichcan occur as the improved medical device 110 is inserted deeper into ahuman body.

[0026] Therefore, the concave slot 115 of the improved medical devicehas a flat surface 125 in the radial cross section of the needle 110 anda curved surface 145 in the axial cross section of the needle 110. Theflat surface 125 in the radial cross section enables the concave slot115 to reflect more of the ultrasound waves back to the transducer,while the curved surface 145 in the axial cross section enables theconcave slot 115 to reflect “off axis” ultrasound waves back to thetransducer.

[0027] Referring to FIG. 4A, the concave slots 115 are arrangedpreferably along the entire circumference of the needle 110. Thisenables the needle 110 to be visualized regardless of the rotationalorientation of the needle 110 with respect to the transducer.

[0028]FIG. 5 is a schematic illustration of another example embodimentof the improved medical device 110 in which concave slots are arrangedin a different pattern on the surface 120 of the improved medical device110. Some of the concave slots 115 are orientated in the same directionas in the example embodiment illustrated in FIGS. 4A-4C, in which theconcave slots 115 have a flat surface in the radial cross section and acurved surface in the axial cross section of the improved medical device110. The rest of the concave slots 165, however, are orientated in aperpendicular direction, in which the surface of the concave slots 165is flat in the axial cross section and curved in the radial crosssection. By arranging the concave slots 115 and 165 in two differentorientations on the surface 110 of the improved medical device 110, theimproved medical device 110 is able to reflect ultrasound waves fromdifferent angles of approach back to the transducer. This increasesflexibility by allowing the improved medical device 110 to be visualizedfrom different angles of entry into a body in relation to thetransducer.

[0029]FIG. 6 is a schematic illustration of still another examplearrangement of the concave slots 115 and 165 on the surface of animproved medical device. The concave slots 115 and 165 may be arrangedin a variety of patterns on the needle to achieve different imageresponses for the improved medical device. In addition, the concaveslots may be arranged in different orientations on the improved medicaldevice other than those shown in FIGS. 5 and 6 to reflect ultrasoundwaves from various angles back to the transducer. In this case, thesurface of each concave slot is flat in one cross section and curved ina perpendicular cross section.

[0030]FIG. 7 is a schematic illustration of a radial cross sectionalview of yet another example of an improved medical device having concaveslots 175. Each concave slot 175 has a bottom surface 180 that followsthe contour of the surface of the improved medical device, such as aneedle. In the example shown in FIG. 7, the bottom surface 180 of eachconcave slot 175 is convex to follow the cylindrical contour of thesurface of the improved medical device. Each concave slot 175 has curvedside surfaces 185 on each end of the bottom surface 180. The curved sidesurfaces 185 reflect ultrasound waves back to the transducer when theultrasound waves 190 approach the concave slot 175 from skewed (i.e.,sideways) angles with respect to the concave slot 175. The curved sidesurfaces 185 may be concave, for example.

[0031] While various embodiments of the application have been described,it will be apparent to those of ordinary skill in the art that many moreembodiments and implementations are possible that are within the scopeof the subject invention. For example, each feature of one embodimentcan be mixed and matched with other features shown in other embodiments.Additionally, the invention may be applied to the surface of othermedical instruments besides needles where it is desirable to enhance theultrasonic visibility of such instruments. For example, the inventionmay be applied to the surface of a catheter to enhance the ultrasonicvisibility of the catheter. Therefore, the invention is not to berestricted or limited except in accordance with the following claims andtheir equivalents.

What is claimed is:
 1. A medical device, comprising: an elongated body;and a plurality of concave slots formed on the elongate body; wherein asurface of each concave slot is substantially flat in a first crosssection and is substantially curved in a second cross section.
 2. Themedical device of claim 1, wherein the first cross section isperpendicular to the second cross section.
 3. The medical device ofclaim 1, wherein the surface of at least one of the concave slots issubstantially flat in a radial cross section of the medical device. 4.The medical device of claim 3, wherein the surface of at least one ofthe concave slots is substantially flat in an axial cross section of themedical device.
 5. The medical device of claim 1, wherein the surface ofat least one of the concave slots is substantially flat in a axial crosssection of the medical device.
 6. The medical device of claim 1, whereinthe plurality of concave slots are formed in a stainless steel portionof the elongated body.
 7. The medical device of claim 1, wherein theplurality of concave slots are formed in a plastic portion of theelongated body.
 8. The medical device of claim 1, wherein the medicaldevice is a needle.
 9. The medical device of claim 8, wherein the firstcross section is perpendicular to the second cross section.
 10. Themedical device of claim 8, wherein the surface of at least one of theconcave slots is substantially flat in a radial cross section of themedical device.
 11. The medical device of claim 8, wherein the surfaceof at least one of the concave slots is substantially flat in an axialcross section of the medical device.
 12. The medical device of claim 1,wherein the medical device is a catheter.
 13. The medical device ofclaim 12, wherein the first cross section is perpendicular to the secondcross section.
 14. The medical device of claim 12, wherein the surfaceof at least one of the concave slots is substantially flat in a radialcross section of the medical device.
 15. The medical device of claim 12,wherein the surface of at least one of the concave slots issubstantially flat in an axial cross section of the medical device. 16.The medical device of claim 1 further comprising a contoured surface onthe elongate body, the plurality of concave slots being formed in thecontoured surface, wherein each concave slot has a bottom surface thatfollows the contours of the contoured surface and curved side surfacesat each end of the bottom surface.
 17. The medical device of claim 16,wherein the bottom surface is convex.
 18. The medical device of claim16, wherein the curved side surfaces are concave.
 19. A medical device,comprising: a contoured surface having a plurality of concave slotsformed thereon, wherein each concave slot has a bottom surface thatfollows the contours of the contoured surface and curved side surfacesat each end of the bottom surface.
 20. The medical device of claim 19,wherein the bottom surface is convex.
 21. The medical device of claim19, wherein the curved side surfaces are concave.
 22. The medical deviceof claim 20, wherein the curved side surfaces are concave.
 23. Themedical device of claim 19, wherein the contoured surface is made ofstainless steel.
 24. The medical device of claim 19, wherein thecontoured surface is made of plastic.
 25. The medical device of claim19, wherein the medical device is a needle.
 26. The medical device ofclaim 25, wherein the bottom surface is convex.
 27. The medical deviceof claim 26, wherein the curved side surfaces are concave.
 28. Themedical device of claim 26, wherein the curved side surfaces areconcave.
 29. The medical device of claim 19, wherein the medical deviceis a catheter.
 30. The medical device of claim 29, wherein the bottomsurface is convex.
 31. The medical device of claim 29, wherein thecurved side surfaces are concave.
 32. The medical device of claim 30,wherein the curved side surfaces are concave.
 33. The medical device ofclaim 19 further comprising a plurality of concave slots formed on thecontoured surface, wherein a surface of each concave slot issubstantially flat in a first cross section and is substantially curvedin a second cross section, the first cross section being perpendicularto the second cross section.
 34. A medical instrument adapted to beinserted into a body, comprising: a surface having a plurality ofconcave slots formed thereon, wherein a surface of each concave slot issubstantially straight in a first cross section and is substantiallycurved in a second cross section.
 35. The medical device of claim 34,wherein the first cross section is perpendicular to the second crosssection.
 36. The medical device of claim 34, wherein the surface is madeof stainless steel.
 37. The medical device of claim 34, wherein thesurface is made of plastic.
 38. The medical device of claim 34, whereinthe medical device is a needle.
 39. The medical device of claim 34,wherein the medical device is a catheter.